The present invention relates to a noncontact information transmitter for transmitting information between an information appliance such as a notebook personal computer or a portable information terminal and an appliance connected for expanding the function of such information appliance.
Portable information terminals, such as various notebook personal computers (hereinafter called notebook PC), a personal digital assistant (PDA) and a personal intelligent communicator (PIC), have recently come into widespread use. These information appliances (or information processing devices) are designed mainly for the purpose of portable use, and when expanding their functions, they are often connected to function expansion devices such as a docking station, a docking unit, a port replicator, and an expansion box. The information appliance, such as the notebook PC, and the function expansion device are physically connected by terminal or the like, and information is transmitted between the devices by the physical connection.
The function expansion devices include a hard disk device, a CD-ROM device, a CR-R device, a PD device, a DVDROM device, a DVDRAM device, other external memory devices, a board mounting CRT display circuit, a board mounting a circuit to be connected to a network, a board mounting a modem circuit to be connected to a telephone circuit, and a board mounting a circuit to extend the signal. A peripheral device can also be connected to the function expansion device. Some of the function expansion devices have a function of supplying power to the notebook PC, built-in peripheral device, an externally connected peripheral device, or built-in circuit board.
Hitherto, as the function expansion device of personal computer, a detachable information processing device as disclosed in Japanese Laid-open patent No. 6-289955, and many others have been known. In such detachable information processing device, a power source is cut off when connecting and manipulating the transmission route, and the power source is turned on after connection, or when cutting off the connection of the detachable information processing device by pressing the eject button, it is necessary to cut off connection after turning off the power source, but the invention is intended to be manipulated by the operator without considering on or off of power source when detaching or attaching.
In the following explanation, the expansion box, docking station, docking unit, and port replicator are commonly called the function expansion device.
A constitution of a conventional function expansion device is shown in FIG. 1l. In FIG. 11, the notebook PC 10 and function expansion device 20 are connected by connecting the mutual connectors.
Inside the notebook PC 10, system parallel buses 211 are provided. The system parallel buses 211 refer, for example, to 32-bit peripheral component interconnect bus (PCI bus), 16-bit industry standard architecture bus (ISA bus), etc. Of the system parallel buses 211, a signal necessary for function expansion (hereinafter function expansion signal) 212 is connected to the PC connector 213 through an input and output buffer 216. The system parallel buses 211 are connected to the internal hard disk device 214 and LCD display device 215.
Inside the function expansion device 20, a function expansion connector 221 and function expansion interface 223 are provided. The function expansion connector 221 is connected to the function expansion interface 223 composed of LSI and circuit, through a function expansion signal 222. The function expansion interface 223 is connected to a peripheral device 224 provided in the function expansion device 20 and a peripheral device 225 provided outside the function expansion device 20. More specifically, the peripheral device 224 is a hard disk drive device or data backup device of high speed and large capacity, and the peripheral device 225 is a camera, printer, or the like.
The operating principle is briefly described below. The notebook PC 10 has basic functions of personal computer alone, and is portable, and is hence used anywhere. On the other hand, the function expansion device 20 has a fixed environmental peripheral device inside or outside by wiring, and it does not function alone, but when connected with the notebook PC 10, it enhances the function of the notebook PC 10 so as to function by processing at larger capacity and higher speed. The notebook PC 10 is connected electrically to the function expansion device 20 through the PC connector 213 and function expansion connector 221. The data stored in the built-in hard disk device 214 is put into the function expansion connector 221 as function expansion signal 212 through system parallel bus 211 and PC connector 213, and, for example, the data is backed up in the peripheral device 224 which is a data back-up device through the function expansion interface 223. On the other hand, a video signal 226 entering from a peripheral device 225 containing a camera passes through the function expansion interface 223, and is reproduced as a camera image in the LCD display device 215 by way of the function expansion connector 221, PC connector 213 and system parallel bus 211.
In the embodiment shown in FIG. 11, the notebook PC 10 and function expansion device 20 are electrically connected to each other. Accordingly, when connecting or disconnecting the notebook PC 10 and function expansion device 20, it was necessary to connect or disconnect after once turning off the power source of the notebook PC 10 and the power source of the function expansion device 20.
To eliminate this inconvenience, a detachable information processing device is disclosed in Japanese Laid-open Patent No. 6-289955. It is intended to turn off the power source automatically by detecting the connecting or disconnecting operation. It is briefly described below while referring to FIG. 12.
In FIG. 12, the notebook PC 10 and function expansion device 20 are connected electrically between the input and output buffers 216 and 231. Depending on connection or disconnection of the input and output buffers 216, 231, a tri-state or open state is established. To realize this, by an interrupt signal 217s emitted from a connection/disconnection detecting device 217, interrupt processing is carried out in a microprocessor 218, and the input and output buffer 216 is set in tri-state by the input and output buffer control signal 218s. Similarly, inside the function expansion device 20, by the input and output buffer control signal 230s emitted from the connection/disconnection detecting device 230, the input and output buffer 231 is set in tri-state or open state. Hence, it is possible to attach or detach without being conscious of power feed or cut-off state.
In this method, the internal processing of the notebook PC 10 may be continuous, and from the viewpoint of software, it does not guarantee the entire operation of the application software.
To improve this point further, U.S. Pat. No. 5,485,488 is disclosed. It is characterized by using the serial interface system called the IEEE1394. In other example, it is also attempted to connect by using universal serial bus (USB). These examples are explained in FIG. 13.
In FIG. 13, the connector of USB is connected at the contact point(s) by means of a receptacle 241 fitted to the notebook PC 10 side and a plug 242 fitted to the function expansion device 20 side. The connector of IEEE1394 is connected at the contact point(s) by means of a socket 243 fitted to the notebook PC 10 side and a plug 244 fitted to the function expansion device 20 side. In the IEEE1394 and USB, by using a twist pair, it is intended to connect plural devices by serial bus. More specifically, the IEEE394 is intended to supply two pairs of power source and signal line to the function expansion device 20, and the USB is intended to supply one pair of power source and signal line to the function expansion device 20.
Both IEEE1394 and USB are known as device bay, and if disconnected during data transmission, or if connected while the power is supplied, it has no effect on the processing action of the PC main body from the viewpoint of hardware and software, and the application software proceeds normally, having no effects on other tasks.
In the conventional device, however, the following problems were known.
First, in the case of parallel bus connection between the notebook PC 10 and function expansion device 20 shown in FIG. 11, it is necessary to use 100-pin connector or 200-pin connector as the connector for connection, and an imperfect connection may occur at the time of connection, and there were problems in reliability such as runaway of the notebook PC 10 during operation. Moreover, because the connection is mechanical, there was a finite life cycle associated with inserting and pulling out the connection. For example, in this kind of connector, the life of inserting and pulling out is about 2000 times, and if inserted and pulled out 10 times/day, it corresponds to 200 days, and it was guaranteed only for a year.
In the constitution shown in FIG. 12, the manipulation for once turning off the power source of the device can be solved, but from the viewpoint of the software, all operations of the application software were not guaranteed. That is, while the application software is in process, it is not allowed to connect or disconnect anytime by force.
The embodiment shown in FIG. 13 can solve the problem of the software, but because of mechanical connection, too, there was also life in inserting and pulling out. For example, according to the USB specification, the minimum life of inserting and pulling out the receptacle and plug is specified as 1500 times. Also according to the IEEE1394 specification, the minimum life of inserting and pulling out the socket and plug is specified as 1500 times. Actually, at a maximum possibility, the life of inserting and pulling out is about 5 times as large, that is, 7000 times. Supposing to be inserted and pulled out 10 times/day and used for 200 days/year, the life is about three years and a half, which is not sufficiently considering the service life of general products is about 6 or 7 years.
Besides, together with the portable information device, the portable function expansion device must be considered, and the mechanical connector not withstanding vibration or humidity involves problems in the aspect of reliability of the appliance.
Also in the case of mechanical connection, when the connector is detached or attached in the power source connected state, the information portable terminal device or function expansion device may be broken down or malfunction due to spark or static electricity.
It is hence an object of the invention to solve the aforesaid problems, and more particularly to present a noncontact information transmitter capable of being detached or attached without being conscious of the state of the power source or software, long in the life of insertion and pulling out, and high in reliability.
To achieve the object, the invention comprises electric signal/optical signal converting means for converting a serial signal into a signal for optical transmission, light emitting and receiving means for transmitting the output of the electric signal/optical signal converting means through a spatial gap, optical signal/electric signal converting means for converting the signal from the receiving means to an electric signal, and serial signal reproducing means for reproducing the output of the optical signal/electric signal converting means into a serial signal.
The serial signal conforms to USB or IEEE1394. It further comprises a spatial transmission core for supplying electric power.
Accordingly, it realizes a noncontact information transmitter capable of transmitting information without using mechanical connection, and connecting and disconnecting without being conscious of the state of the software or power source at all.